This section provides background information related to the present disclosure, not necessarily being conventional technology.
Requirements on data transmission rate and transmission efficiency are increased with an explosive growth of the amount of user data, and a load of communication between a user and a base station is increased constantly. D2D (Device-to-Device) communication technology is proposed under the background. The D2D communication technology refers to an information transmission mode in which cellular communication user equipments perform data interaction directly in a terminal-through manner. Compared with the conventional cellular communication, in the D2D communication technology, frequency spectrum resources are multiplexed, the transmission distance is shortened, and the information is not necessarily forwarded via a base station, thereby improving a spectrum use and decreasing a transmission power of a user equipment and a load of the base station. Moreover, the signal has better quality due to the short communication distance, thereby reducing communication interference to other devices.
However, the D2D communication changes a conventional communication mode of user-base-station, some functions of the base station are transferred to the user equipment, hence, it will be a challenge to design a physical layer, a MAC (Media Access Control) layer or a high layer protocol. Particularly, power control in the D2D communication needs to be further regulated and designed.